First priority would be to get a dragon solo build going. For that, you need to put him in a regen set. Usually people got for stage 25, but if you're having gear trouble, stage 21 is a good intermediate point.

I cannot really farm good regen set yet, I'm on FK 13 only. I mean I could farm regen gear, but that would take a lot of time, cause my inefficient team and long runs. That's why I want teams that can farm stage 20s in dungeons. After that I can think about make him solo dungeons, but that's not close

Hmm, maybe you can pair him up with a healer/tank in the meantime. Maybe miscreated monster? That would be optimal in terms of affinity to protect your Teodor. I think this duo should be able to clear stage 21.

Edit: you also have Korugar who might be able to do the job.

I cannot book him out. That makes things quite hard... I have to save up more lego booksa

Was in the same situation pretty much,but i was pretty dumb and tried to farm regen and wasted a lot of time :C